4.17 The Detour-Delta Matrix

The entries in the detour-delta matrix, denoted by ΔDM, are related to the elements of the corresponding detour-path matrix as the entries of the vertex-distance-delta matrix are to the elements of vertex-distance matrix.

[ΔDM]ij=
[DM]ij          if ij
2
     
  0                       otherwise                          (68)    

The detour-delta matrix enumerates the number of all the longest paths larger than unity between vertices i and j in a graph.

The ΔDM matrix of G1 (see structure A in Figure 2) is given below.

ΔDM(G1)=
0
0
1
10
6
10
15
0
0
0
6
3
6
10
1
0
0
3
1
3
6
10
6
3
0
3
2
3
6
3
1
3
0
3
6
10
6
3
2
3
0
0
15
10
6
3
6
0
0

The following relationship is between the elements of the three matrices based on the longest graph-distances DM, pDM and ΔDM:

[pDM]ij=[DM]ij + [ΔDM]ij                         (69)   

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